Inexperienced referees "have gone berserk" in imposing yellow cards after a new law was introduced in 2017, says ex-Wales star Jonathan Davies.

The rule states that any contact with the head in "reckless tackles" will be penalised with at least a yellow card.

Pro12 players from Ulster, Scarlets and Ospreys were sin-binned this weekend.

Davies told Scrum V: "It's a brilliant directive but it's not being refereed properly. They've gone to the letter of the law, and it's gone crazy."

The former union and league player wants referees to adopt a common sense approach, adding: "You know a high shot, you know a cheap shot, you know a fair shot and referees have got to understand the difference as well."

In September 2015, World Rugby's chief medical officer Martin Raftery told the BBC that the game's laws may have to change to reduce concussions.

On Friday, Ulster's Sean Reidy was sin-binned for a tackle on Scarlets scrum-half Aled Davies in their 16-13 defeat in Llanelli.

Davies and fellow Scrum V pundit Sean Holley said Reidy should not even have been penalised.

They also believe Ulster captain and wing Andrew Trimble's attempted tackle on Aled Davies in the same passage of play, which appeared to connect with his head, warranted a yellow card, but went unpunished.

Scarlets lock Jake Ball was also sin-binned in that game - another decision that drew the ire of Davies and Holley.

"Sam Davies goes into the tackle, he goes low, the player's falling on him because he's being dragged down and he (Sam Davies) hits and it's a yellow card," Davies said.

"It will be interesting to see if something like that crops up in England v Wales (in the 2017 Six Nations).

"Say England score a try or Wales have a player sent off for 10 minutes and lose the game, there's going to be absolute ructions."

Pundit Davies' brain-damaged cousin

Davies also spoke of a cousin who he says has been in a coma and suffered brain as a result of a tackle in a match.

The former Neath, Llanelli and Wales union player, said: "He made a tackle, a legitimate tackle under the hip and he got injured.

"So now we're worried about the ball-carrier, not the tackler.

"So if you're going down and (the attacker is) leading with an elbow and the knee or the hip, then the tackler's in danger of getting damaged as well."

Sarries controversy

Former Ospreys head coach and Bristol assistant Holley fears some fans will lose interest in the game if the trend continues.

He disagreed with Saracens boss Mark McCall, who described Richard Barrington's sending-off in their Premiership draw with Exeter as neither reckless nor dangerous.

Holley said it was a "dangerous effort".

Referring to events in the Scarlets v Ulster game, Holley said: "What Sean Reidy's done there is try to prevent the score, which is ultimately his job and it's, in our view, a good tackle - it's not even a penalty let alone a yellow card.

"Trimble's is perhaps the more malicious, dangerous one.

"As for Jake Ball and Sam Davies, crikey, we're going to switch people off the game here if we are going to be stopping the game and sending people off for that."